The present invention relates in general to improved treatment for fractures of the femur and in particular concerns apparatus and methodology for the efficacious treatment of the highly problematic combination of a femoral shaft fracture with an ipsilateral femoral neck fracture (i.e., femoral hip region fracture).
The femur or thigh bone is the largest and longest bone in the human skeleton. In general, it comprises two extremities connected by an elongated fairly cylindrical shaft. The upper or proximal extremity may be broadly regarded as constituting the hip region.
Generally speaking, fracture injuries to the femoral shaft have been primarily treated (per current acceptable methods) with various intramedullary rods or nails. An intramedullary rod is an elongated member which is introduced to and resides in the marrow of the femur for the purpose of stabilizing the fractured femoral shaft. It is desired that stabilization take place in conjunction with anatomic reduction (i,e., proper reorientation of fractured elements to their original position, both relative to one another and relative to other adjacent anatomical features). As well known to those of ordinary skill in the art, installation of intramedullary rods often involves passage through the upper extremity or hip region, and in fact results in the proximal end of the rod occupying a significant portion of the hip portion of the femur.
It is possible to sustain fracture injuries not only to the femoral shaft, but also to one or both of the femoral extremities. Of particular present concern is the occurrence of a fracture to the upper extremity, particularly to the head or neck regions of the femur. The primary problem addressed by this invention occurs whenever a femoral neck fracture (or any femoral hip region fracture generally) occurs at the same time and in the same femur (ipsilateral fractures) as a femoral shaft fracture. A straightforward problem arises from the fact that the standard presently acceptable treatment for femoral neck fractures primarily involves the use of bone screws which are introduced (at various angles and locations) to the femoral hip region. Thus, there exists literally a physical interference between the standard intramedullary rod provided for treating a femoral shaft fracture and the standard bone screws provided for treating a femoral hip region injury. Less apparent but just as serious problems and complications also arise due to the practicalities of installation procedures accompanying the use of such two standard techniques.
Therefore, a major problem exists in instances of ipsilateral femoral shaft and hip fractures in that the standard acceptable treatments for respective femoral shaft and hip fractures are substantially mutually exclusive. At present, there is no standard accepted treatment method for ipsilateral femoral shaft and hip fractures, despite the availability of numerous different approaches. In some instances, the treating doctors even choose to forgo treatment of the shaft fracture until at least partial recuperation of the hip fracture, since highly precise fracture reduction is not as critical in the femoral shaft as it is in the hip. In other words, if the doctor thinks in a given situation that he cannot "fix" both problems in an ipsilateral fracture case, he or she may risk potential negative consequences of poor shaft fracture healing (e.g., limp or discomfort from shortened leg or misalignment) versus potential negative consequences of poor hip fracture healing (e.g., artificial hip replacement surgery).
The difficulties of the central problem may be better comprehended with a more detailed understanding of the anatomical considerations and of exemplary prior treatment approaches and drawbacks. The following very briefly outlines pertinent anatomical terminology with reference to present FIG. 1. FIG. 1 illustrates a generally anterior (front) surface view of a right human femur generally 20. Femur 20 is comprised of an inferior or distal extremity generally 22, a superior or proximal extremity generally 24, and an elongated generally cylindrical shaft 26 connecting the two opposing extremities. In the anterior view of present FIG. 1, the medial side of femur 20 is generally the right-hand illustrated side while the lateral side thereof is generally the left-hand illustrated side in the view.
The superior extremity generally 24 includes a number of separately recognizable features of present interest, including a head generally 28, a neck region generally 30, and greater and lesser trochanters generally 32 and 34, respectively. The greater trochanter is a relatively large and somewhat irregular eminence located above the top of the shaft and towards the lateral side of the neck, while the lesser trochanter constitutes a somewhat smaller (but of variable size in different patients) projection from the relatively lower and posterior (back) side of the femoral neck. Generally speaking, the "hip" may be regarded as comprising the features proximal to (i.e., above) the lesser trochanter 34.
Though not shown in detail in the illustration of present FIG. 1, a slight surface crest extends anteriorly and posteriorly between the trochanters 32 and 34. Also, an imaginary line or plane extending between the greater and lesser trochanters is referred to as the intertrochanteric line. Fractures can occur in may varieties in the hip. Generally speaking, fractures occurring between the intertrochanteric line and the head 28 are referred to as neck fractures. An intertrochanteric fracture is one generally in alignment with the intertrochanteric line, while a pertrochanteric fracture is one which resides at least in part in the neck region but which crosses the intertrochanteric line. A subtrochanteric fracture is still in the hip but at least partly below the intertrochanteric line.
Fracture patterns are the subject of much study and analysis. For example, one classification system referred to as Pauwels' classification grades femoral neck fractures into three types, depending on the angle the fracture forms with an imaginary horizontal plane resting across the extreme proximal end of the femur. Determination of such classification in a given instance (such as from x-rays or the like) helps the treating physician determine the desired positioning of femoral neck screws for treatment of the fracture. Generally speaking, greater strength is established whenever the screws normally address (i.e., are perpendicular to) the fracture line. Hence, the nature of the hip fracture can dictate the desired (or required) positioning of screws in the hip region, which indicated positions can be in conflict with the needed placement or effective space requirements of a standard intramedullary rod for treating an accompanying shaft fracture.
Also, a lateral view x-ray is virtually required to insure satisfactory anatomical reduction of a femoral neck fracture. However, many of the currently available shaft nail systems incorporate structures, such as a lateral fixation plate or similar, which literally would block the necessary x-ray view. See, for example, U.S. Pat. No. 4,506,662 issued to Anapliotis, and illustrating an exemplary attachment plate 40 in FIG. 4 thereof. FIG. 2b of such '662 patent also illustrates a technique referred to as "bundle" nailing, which can literally block out (or fill) an entire hip region to the exclusion of femoral screws needed for treatment of a femoral hip fracture.
Femoral shaft fractures are likewise the subject of much study and analysis, and can be variously classified. One accepted system is referred to as the Winquist-Hansen Comminution Scale, which focuses attention on the cortical damage to the femur. The femur is comprised of cortical bone, which is the dense rim of bone forming portions such as the annular portion of the shaft, and of marrow, which is the soft bone tissue received in the internal cavity defined by the cortical bone. On the Winquist-Hansen scale, a first type injury involves a fracture (i.e., break) to cortical bone in the shaft. The next higher level injury involves some loss (through absence, crushing, pulverizing, or other destructive effects) of the cortical bone, but less than fifty percent loss in a given region. The next higher type of fracture involves the same damage characteristics as above, but with greater than fifty percent cortical bone loss in a given region. The next higher type of injury involves trauma to such an extent that there is no remaining cortical bone contact in a given region. The highest type of injury on the communition scale involves actual segmental bone loss.
The importance in understanding the above-described progressive degrees of injury which can result from trauma to the femur arises from understanding the corresponding conventional treatments thereof. Generally speaking, the goal of any fracture treatment is to provide a stable and complete anatomic reduction (i e., "setting") of the fracture.
As the nature of a fracture is progressively more severe, as described above, the treatment approaches become more complex and more difficult to administer. For example, one of the more simple approaches to treatment of femoral shaft injuries involves the use of relatively smaller diameter, or in some instances, even flexible, intramedullary rods. A smaller diameter rod is typically less strong but may avoid the need to literally ream (i.e., cut) out a channel inside the femur for insertion of the rod. Sometimes, an anatomic reduction of adequate mechanical stability can be achieved through the introduction of a guide wire or similar in the top of the shaft and down through the bone marrow, followed by introduction of a cannulated (i.e., hollow) femoral nail or rod over the top of the guide wire. However, an inadequate biomechanically stable fixation pattern can result in various complications, such as non-union or malunion, or even shortening and malrotation. In worst case complications, there can be osteonecrosis (tissue death). Even in younger patients, such events can lead to the need for hip replacement surgery (highly undesirable for any patient, but regarded especially as potentially devastating to younger patients).
To satisfy reduction and stability needs, femoral shaft injuries, particularly those of greater severity, often entail treatment with larger diameter or more stiff femoral nails, which can involve reaming techniques for placement of the nail. Such techniques literally involve reaming out part of the femur interior to be followed by installation of the nail. In many instances, so-called second generation or reconstruction nails ("recon"nails) are utilized, which typically involves interlocking steps of inserting screws through the leg and femur into holes in the nail to secure the position of both the femur and the nail. Special targeting devices, assistants, and experience can be required for blindly seating interlocking screws inside of a femur.
In some patients, the use of intramedullary nails in an unreamed femur may be adequate for the treatment of inherently stable fractures, but the use of intramedullary nails in a reamed femur and/or the use of interlocking femoral nails are standard treatments for more severe injuries. A readily apparent drawback of such technique, however, relates to the installation process, being both costly in terms of the required special instruments, and for the personnel who must have special surgical training, and additional assistants. Since worser or worst case traumas typically occur less frequently, doctors tend to have (and can expect to have) generally less experience with the more severe situations. Such fact only compounds the difficulty of, for example, night time emergency room treatment of ipsiiateral femoral fractures.
It has been reported that as many as 2.5 percent to 5 percent of femoral shaft fractures occur in combination with (i.e., ipsilaterally) with femoral hip fractures. Moreover, such combination fractures most often occur as a result of high energy trauma. The above description of standard treatments of more progressive fracture types (i.e., most likely occurring due to relatively higher energy trauma) provides a background for understanding the considerable difficulty of treating ipsilateral fractures. High energy trauma to the thigh region can occur in a variety of ways, such as due to high speed motorcycle accidents, car accidents, or falls from a relative height.
One exemplary analysis of high energy trauma leading to ipsilateral femoral fractures is as follows. The energy or force from a given traumatic impact must be dissipated somewhere or somehow. Very frequently, such dissipation takes the form of a fracture (i.e., break) in the femoral shaft, typically medial or distal thereto. If excess energy exists after partial dissipation through a femoral shaft fracture, then further energy dissipation must take place.
The femur or thigh is in an adducted position whenever the legs are close together and generally aligned with the trunk of the body. The femoral head resides in and articulates in the acetabulum. Whenever the femur is in such adducted position, excess energy dissipation often results in the hip being dislocated by escaping from the acetabulum. However, if the femur is in an abducted position (i.e., with the leg turned out or open, such as a rider on a motorcycle), the hip region of the femur cannot escape from the acetabulum and therefore must absorb the excess energy to be dissipated. Such events can result in one of the various hip fractures as described above, such as a neck fracture, intertrochanteric fracture, or other.
Other traumatic events can cause ipsilateral fractures "in reverse," (i.e., with the femoral hip fracturing before the femoral shaft. Resulting treatment complications are roughly the same, regardless of the originating trauma.
A generally accepted treatment for stabilizing femoral neck fractures is the use of multiple lag screws, such as in a triangular or some other deliberate pattern designed to gain needed fixation stability. However, reports indicate that as many as one third of the femoral neck fractures may be missed from an initial diagnosis. This means that a standard intramedullary nail may have already been used to fix a femoral shaft fracture, and therefore occupies the space in the hip within which the multiple lag screws should be inserted. Such an occurrence results in attempted placement around the prepositioned nail, but such approach can lead to inadequate mechanical stability for the femoral neck fracture. If, for example, Ender nails are utilized (nails which are placed upwardly through the distal end of the femur; see, for example, U.S. Pat. No. 4,055,172 issued to Ender et al.), there may be an inadequate and unstable anatomic reduction of the femoral shaft fracture. Therefore, no satisfactory standard treatment exists for treatment of the ipsilateral shaft and hip fractures as described above.
Traumatic injury of sufficiently high energy to cause ipsilateral femoral shaft and hip injuries may well result in multiple injuries or compound trauma to the patient. Significantly, pertinent literature analyzing and advocating various treatments of trauma patients has revealed handling of femoral fractures (i.e., stabilization thereof) to be an integral part of the overall resuscitation of such a trauma victim. Early stabilization of femoral fracture conditions has been shown to decrease the incidences of acute respiratory distress syndrome and death. Hence, there is potentially a great deal at stake whenever treatment standards have heretofore been generally unable to address particular fracture patterns (i.e., ipsilateral femoral shaft and hip fractures) occurring most typically in trauma victims of the type most likely to also have other trauma related complications (i.e., multiple or compound injuries). Given such facts, it should be all the more apparent that treatments which involve time consuming, complex, or unfamiliar skill specific procedures are all the more contraindicated.
The patent literature describes different attempts at treating various femoral fractures, and thus provides additional background in this area. Further examples of such patents are:
______________________________________ U.S. PAT. NO. INVENTOR ISSUE DATE ______________________________________ 2,761,444 Luck September 4, 1956 4,705,027 Klaue November 10, 1987 4,817,591 Klaue April 4, 1989 4,846,162 Moehring July 11, 1989 4,865,025 Buzzi et al. September 12, 1989 4,877,019 Vives October 31, 1989 4,988,350 Herzberg January 29, 1991 ______________________________________
The disclosures of all the above-listed and above-referenced U.S. Patents are fully incorporated herein by reference.